At one point in time, all bicycles were constructed the same, allowing for part swapping and easy part replacement. However, many parts are now defined as either British or metric, with metric being commonly referred to as "French." Certain parts on metric and British bikes differ, while some small items remain interchangeable. Many of the bicycles imported into United States are made of English or British screwed threads, bottom bracket threads, headset grades and headset mounting diameters.
Similarities
On British and metric bicycles, the brakes, saddles, pumps and bottle cages are manufactured with the same standard. If any of these parts break on your bicycle, whether they're metric or British pieces, either can be used to fix it. Author John Forster states that increasingly over the years, the number of standards has multiplied in the form of brand standards, while the choices within any one standard have been diminished, resulting in cyclist having less choices. He also states in his book "Effective Cycling" that it's more difficult for individual cyclists to order or assemble a bicycle suitable for his own usage because many of the parts differ.
Frame Tubing
Bicycle dimensions are divided into two standard groups: British and metric. The metric standard dimensions are commonly referred to as French; however, Italian and Swiss standards are also referred to as metric and both differ slightly from French dimensions. The biggest difference in the standards, according to the book "Effective Cycling," is in the frame tubing and the parts that connect to the frame. This difference is so vital that once your bicycle has been made, it's impossible to change the dimensions of the frame tubing or additional frame parts.
Frame and Pedals
Both metric and British bicycles have different pedal threads and pedals and the French and British bicycles differ in seating and derailleur clamps. Since metric bicycle frames have lighter weight tubing and thinner walls, the seat posts different from British bicycles. The French bicycles are available in six different sizes.
Handlebars
Both British and French bicycle handlebar stems differ. The difference in the stems and the steering column holding the stems calls for a difference in bearing sets. The handlebars come in three separate dimensions, although the brake levers contained on the handlebars will fit both the French and British bicycles, since there's no difference in the brakes.
Posted in: Bicycling